I am a complete novice so need someone with the knowledge to help me out...

I have just bought a couple of cheap Chinese MP4 players for my kids (3 + 5 years) with the intention of keeping them quiet on a long road trip. I want to load them up with videos. They were very cheap and cheerful so might just be a hunk of junk but perfect for my two little ones...

Anyway, I have downloaded the encoding software recommended by the seller but when I encode stuff (even at the highest 208x176) it doesn't even come close to full screen.

The weird thing is that the demo video on there is done at 160x120 and it fits full size.

Why do my 160x120 come up tiny? Is it my original source material?

Any help would be great - it's just weird that their 160x120 is full screen but mine is small in the middle? I've tried a couple of different encoding softwares but all do the same...

I'll preface this by saying that this site has nothing to do with the .amv format/container, nor with the Chinese "MP4" players that use the format.

That said, we still may be able to help you out.

I'm assuming that your video players are fullscreen (4:3), as you say that the demo 160x120 video fully fills the player screen, and that you really don't care to get into technical details.

Giving the benefit of the doubt to your media player, it's most likely an issue with your source. If your source is widescreen (16:9), your fullscreen player will display bars on the top and bottom (this is called letterboxing). If your source was originally fullscreen, but some schmuck decided to make it widescreen by adding bars to the left and right sides (this is called pillarboxing), then your player will again add bars to the top and bottom, making the end result windowboxed.

Either way, the solution is to:
1-crop the video to get rid of the black bars
2-crop the video again so that source width / source height = 4/3
3-resize the video to 160 x 120

If your encoding program (by the way...which one(s) have you tried?) can't do all of those things you need to find an encoding program that does that either gives you the proper filetype, or gives you a filetype that your current program can accept.